1. Field of the Invention
The present invention relates generally to solar arrays. More specifically, the present invention related to solar arrays for space craft that can be easily stowed during launch, have a minimal volume, and easily deployed to a desired size having a high degree of stiffness and stability.
2. Description of Related Prior Art
Solar arrays are used for space vehicles and satellites to generate current for power. The capacity of the solar array to produce current is directly related to the exposed surface area of the array having solar cells thereon. A solar array needs to be stowed during launch of the space vehicle or satellite occupying a minimum volume, having a minimum weight for subsequent deployment, and having a maximum surface area having solar cells thereon for current generation.
Solar arrays used for space vehicles need to achieve a high degree of stiffness and stability after deployment which runs counter to having a minimum volume and minimum weight when stowed for launch and deployment. Since a circular arrangement offers the maximum deployed area with the highest deployed stiffness, one type of solar array tends to be a multi-panel solar array having the general shape of a circle having triangular solar blankets, or gores, of the solar array being folded for deployment. In this manner, the gores can be supported and deployed about a hub being attached thereto by means of spars attached to brackets attached to the hub.
Alternatively, rectangular types of solar blankets may be used where the blanket is folded in an accordion arrangement for deployment between panels connected by a hinged pantograph or deployable boom deployment structure.
U.S. Pat. No. 5,296,044 to Harvey et al. describes a solar array deployable from a flat triangular structure to a substantially circular deployed shape. A static panel spar supports a hub having a plurality of intermediate spars rotating freely around the hub. A foldable gore is fitted between each pair of adjacent spars except between the static panel spar and the pivot panel. Rotation of the hub in one direction folds the gores into a stack. Rotation in the opposite direction opens the gores to form tensioned membranes between the spars.
U.S. Pat. No. 6,637,702 to McCandless describes a solar array including a plurality of panels that are individually supported by beams that nest within each other in the stowed position to minimize the volume of the structure. The beams are pivotally connected to each other being deployed by conventional means.
U.S. Pat. No. 6,423,895 to Murphy et al. describes a solar array including a blanket folded into adjacent panels that are hinged in an accordion-folded mode at parallel hinges. A pair of foldable spines is fixed to the panels and runs the length of the array. The hinges are included in the spine. The spines are mounted to a base plate attached to a space craft and to a tip plate. A pantograph deployment structure is used to retract and extend the blanket. A conductive harness is attached to the blanket to collect current from the panels.
U.S. Pat. No. 5,578,139 to Jones et al. describes a stowable and deployable concentrator for solar cells. A row of Fresnel lens elements is mounted to a substrate to be deflectable toward the substrate in a stowed configuration and biased away from it in the deployed configuration.
U.S. Pat. No. 6,624,351 to Kular et al. describes a folding photovoltaic strip device comprising a plurality of photovoltaic modules joined to form a strip and pleated by flexible, transverse creases so that the device may be stored folded together along the creases. The creases are sprung open to expose the modules to light.
U.S. Pat. No. 6,689,952 to Kawaguchi describes a membrane space structure deployed and spanned by centrifugal force owing to a spin motion. The structure includes a hub and a sail having plurality of petals attached to the hub by supports. Membranes are divided into suitable shapes where adjacent membranes are discretely connected to each other by bridge belts to suppress the residual crease strain. The petals may be connected to each other to help deployment.
U.S. Pat. No. 5,833,176 to Rubin describes a bowed solar array including panels that are connected by hinges. When stowed, the panels fold onto each other in an accordion fashion so that they occupy minimal volume in comparison to when the panels are deployed. A tensioning mechanism includes pulleys associated with the panels, and cables inter-connecting the pulleys of the array. The bowed panels and tensioning mechanism are used to attempt to increase deployed stiffness.